In support of Pagell and Wu (2009) findings the researches of (Craig & Rogers, 2008; Rao & Holt, 2005; Sarkis, 2003; Veleva et al., 2003) showed that all companies were concerned with environmental and financial sustainability through the reduction of carbon dioxide during transportation.
The methods used by the ten companies to reduce this effect during operations were to optimize their vehicles. Vehicle optimization was attained through energy and fuel efficiency and reduction in emissions by means of technological innovations for vehicles. They also made use of new aerodynamics and frequent maintenance of machines as a way to achieve sustainability. Green transportation was identified by all the companies as the main source of economic sustainability.